I am facing an issue with a Kotlin coroutine. When I run the following suspend function : performTask, I notice that the log message “Step 1: Task within withContext” is printed first, and only after 10 seconds, the message “Step 2: Task outside withContext” is printed.

Here’s the code:

suspend fun weirdFunction() {
    CoroutineScope(coroutineContext).launch {
        delay(10_000)
    }
}

suspend fun performTask() {
    withContext(Dispatchers.Default) {
        weirdFunction()
        Log.d("MyTag", "Step 1: Task within withContext")
    }
    Log.d("MyTag", "Step 2: Task outside withContext")
}

I believe the issue is caused by using CoroutineScope(coroutineContext).launch inside weirdFunction, but I don’t understand why this usage leads to this behavior. My intention was to launch a child coroutine within the current coroutine scope without passing the scope as a parameter. I thought using coroutineContext to obtain the current coroutine scope was an elegant way to achieve this.

However, it seems my understanding might be incorrect. This issue made me think about a more concerning scenario: if weirdFunction were part of a third-party library, it could cause withContext to hang and not return as expected, which would make debugging very difficult.

Could someone explain why this approach causes the withContext block to wait for the launched coroutine to complete? Is there a better way to launch a non-blocking coroutine within a suspend function that doesn’t affect the caller’s coroutine scope? Any insights or explanations would be greatly appreciated.